Lock issue title and description forever

Background

Enterprise organizations often have strict rules on developing requirements and tracking work.

One use case is developing a set of requirements. Once the set of requirements have been reviewed and approved, they can never be changed. If there needs to be any amendment, there would be another set that amends the original set. But the original set cannot be changed, because it has already been reviewed and approved. This is to maintain a strict change control process.

Proposed feature

We use the issue title and issue description to maintain a set of requirements.

During the discussion and analysis phase, the title and description can be changed as usual.

When it is time for final approval, one user (in this iteration, it can be anybody who has access to edit the issue), makes the final changes to the title and description. And then that user clicks a special UI, and forever locks the issue title and description.

There is a system note to document who did the lock, and when.

The issue title and description can never be changed. At most, the issue could be deleted per the outcome of (gitlab-ce#32619 (closed)).

There is some UI (probably next to the issue title), that indicates it is locked forever. When you click the UI (maybe an icon or a link), it navigates to the system note associated with the lock action.

Everything else works as normal for issue. You can continue changing attributes labels, assignees, everything in the sidebar. You can continue adding comments. The only thing that cannot be changed is the issue title and description.